New answers tagged gpio
4
There is nothing wrong with the GPIO, it just can't supply enough current for your coil.
If the coil has just 24Ω, at a 3,3V the GPIO would need to supply 137mA.
This source at raspberrypi.org says that the maximum current it 51mA for all GPIOs together and 16mA per GPIO.
You can connect the GPIO to a transistor that can supply the necessary 137mA.
4
No it is not possible to toggle the power rails in software.
They are both powered whilst the Pi is powered.
Look at the schematics for your model here.
0
You need to pull the GPIO to either 3V3 or ground in each switch position.
If you connect one end of the switch to ground it would be normal to connect the other end of the switch to a GPIO with a pull-up to 3V3.
If you connect one end of the switch to 3V3 it would be normal to connect the other end of the switch to a GPIO with a pull-down to ground.
You ...
0
Question
Can Rpi interface with MicroBit over GPIO?
Can Rpi interface with MicroBit over Serial?
Short Answer
Yes, no problem at all. I would suggest to start with UART serial,
using Rpi python on one side, and MicroBit MicroPython on the other
side.
Long Answer
Brainstorming comments
I played with MicroBit a couple of years ago, ...
2
The problem is Python's variable scope.
The canExit variable in the onButtonPress function is not the same as the canExit variable in the outer scope.
To use the outer scope variable you need to specify canExit as global as follows.
def onButtonPress():
global canExit
print("button pressed")
canExit=True
print("end of logic")
1
In your program, you turn canExit to True on button press, but I don't see you use that to exit the program anywhere.
import sys
sys.exit()
This is a standard way to exit programs in Python, and I see you use this in cleanup(), and you call cleanup() at the end of your code. You can use an if or while to check the status of canExit, and then execute sys....
1
You need no external circuitry to control it, just a 12V power supply.
You then connect the fan's pwm input to your gpio which has to generate a PWM at 25kHz (intel standard for pc fans). Keep common ground between the fan and the raspberry.
6
That's exactly what interrupts do. In python there is a function RPi.GPIO.add_event_detect( GPIO_NUMBER, GPIO.RISING, callback=yourCallback). You then need to define a function yourCallback() where you manage whatever has to happen when the respective gpio senses a RISING edge. A websearch for "raspberry pi gpio interrupt" will reveal several detailed ...
0
As an addition for Andrey Volkov's answer, new Debian system has a set format for the init script. Please refers to here
With that I have made a script that should work on your system.
Name the following script gpio_init and chown to root.root and chmod to 755. Copy it to /etc/init.d/
#!/bin/sh
### BEGIN INIT INFO
# Provides: gpio_init
# ...
5
The pigpio library lets you control the GPIO of one or more networked Pis from a laptop. The laptop may be Windows, Mac, Android, or Linux based - in fact it can run any operating system as long as it can run Python. The pigpio Python module allows control of the remote GPIO.
pigpio will let you properly control servos. It provides hardware timed PWM (...
-3
Question
Face tracking using laptop usb cam, opencv and dlib
Face motion signal from laptop to Rpi to use GPIO to move servo motors.
Is this config OK?
Answer
I think it is a good use of laptop and Rpi. To know more about how to
use Rpi's PWM GPIO pins to move servo motors, you might like to read
my answer in the following post.
Using ...
2
the spike caused by motors, drops the controller voltage.
in this case (the pi), it will drop to 4.6 v for example, which is enough to cause to to reboot.
either use an adapter for rpi, or give it another clean power source.
plus, for the same reason DIY quadcopters have separate batteries dedicated for the controller.
2
This question is unanswerable - depends on the undefined IR remote receiver.
Pin 5 (BCM 3) is just another input (by default) but is probably a poor choice, as it has a 1.8kΩ pullup, and the receiver may not be able to pull it down.
Pin 5 can be used to reboot the Pi (but AFAIK should not affect the Pi unless shutdown - but I have never tested this)
Name: ...
0
GPIO numbered 0 to 53 correspond to Broadcom GPIO numbered 0 - 53.
See https://pinout.xyz/ for the correspondence between GPIO number and Raspberry Pi extension header pin number.
If you are using the new gpiochip interface (rather than the sysfs interface) this assumes you open gpiochip0.
1
Question
Convert linux C++ printer program to Rpi python
Answer
The slightly tricky part is that Rpi has no write 8 bit port function.
So we need to DIY our own virtual 8 bit port by abstracting 8 GPIO
pins as one fake 8 bit port. We can then write a fake write fake 8
bit port function, ...
References
Centronics/Parallel Port Printer Cable - ...
3
If I had to do this, I would use a 100ns 62256 SRAM chip and added some dual-port logic made from six 74244/74245 chips to it.
Then, I would use an additional µC, e.g. an ATtiny85 or such and clock it with the 4.77 MHz 8088 clock, so the RAM could be accessed by both CPUs in an alternating fashion. The RAM port is flipped with the 8088 clock, too. That way, ...
-2
Question
I am testing out this new birthday present I got ages ago
GPIO pins do not appear to go into the raspberry pi
Answer
Introduction
Ah, we never heard of the thing called "Snap Circuits", so everybody made wrong guesses. In order to save our losing face and restore Rpi StackExchange's before damaged reputation, I am now preparing an answer. ...
2
It turns out I was using the wrong Library. The device I have is a SH1106, not a SSD1306. When using the proper library (Like this one) It works fine.
1
Working with 240VAC is a risk, so pay attention to carefully isolate all 240V wires before giving voltage!
A possible solution, safe for the raspberry inputs, is to add an optocoupler
connect the 240VAC to a capacitance of 100nF/630v in series with a safety resistor of 3900ohm 1/4W. The capacitance has an equivalent resistance of 33k and dissipate very ...
1
It's as simple as adding a simple resistor to limit the current flowing to the GPIO.
What we shall be carefull is to limit the current flowing "to" the GPIO, worst case when the input is 5V .
Three steps:
define the GPIO pin as input.
Add a pull_down. Thanks the BCM2836 design, each GPIO pin has an internal pull down resistor SW enabled. This pull down has ...
3
Digital_Rookie -- Welcome.
The (obvious) answer would be to get female to female cables. I usually keep all three types of sets M-to-F, F-to-F, and M-to-M handy. eg.
https://www.amazon.com/EDGELEC-Breadboard-Optional-Assorted-Multicolored/dp/B07GD2BWPY
0
It is possible (in principle) to detect 5V with a voltage divider, but connection to an external device introduces many additional issues.
The Pi GPIO typically changes state at ~1.2V - but no engineer would rely on using it to do more than determine ON/OFF. It is safe to assume <0.8V is off >2.0V is ON. See Voltage Levels
I normally design voltage ...
0
It depends.
If you know the maximum possible voltage, say X. Then a voltage divider changing X to 3V3 will work and will be safe. This assumes that 5V is sufficiently close to X so that it will also be detected as high (so the voltage divider should turn 5V into something like at least 2.5V).
If you are ultra cautious use high value resistors in the ...
1
Question
I have a python program running a loop of two functions "talking" to each other.
Let us call the two functions Function 1 and Function 2, and they are doing similar things as briefly described below.
Function 1 takes care of two Rpi GPIO pins, input pin GPIO In1 is connected (through a 4k7 resistor) to output pin GPIO pin Out2, which is
...
1
So apparently the only problem is that the lirc drivers are outdated and not present in newer versions of raspbian. Just change that to the new gpio-ir-tx driver and all will work fine. Also note the syntax for the pins changed slightly. I.e, this is what you need in your /boot/config.txt
dtoverlay=gpio-ir-tx,gpio_pin=23
0
Question
WittyPi2 on Pi Zero W Raspbian Stretch - I2C read / write fail
The Pi can do one round of shutdown/start-up, but after this point the I2C errors begin.
However, this works absolutely fine on my 3B.
Answer
Well, if WittyPi2 works well with Rpi3B but not RpiZero stretch, then the problem is with RpiZero.
The WittyPi2 user guide ...
1
A GPIO set as an input will float (read randomly low/high) until a voltage is applied.
The simplest thing to do is set the internal resistor pulls to the opposite of the value set by the switch.
If I read your circuit correctly use
GPIO.setup(green_led, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
0
try the code below(untested)
import time
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
G = 17
R = 27
GPIO.setup(G, GPIO.IN)
GPIO.setup(R, GPIO.IN)
i=1
while (i<10):
if(GPIO.input(r)==HIGH):
print ('RED led is active')
if(GPIO.input(g)==HIGH):
print ('RED led is active')
1
Getting GPS's Data: GPS receives data from output NMEA0183, tcp: // 2947, class: TPV & amp; tag: GPGGA.
Next is the step in the terminal to access GPS data:
Install: gpsd, gpsd-clients. (Note: install both use apt-get install)
Reboot (sudo reboot or sudo init 6)
Sudo dpkg-reconfigure gpsd (Note: configuration baudrate = 9600, 8 N 1 data format).
Serial ...
0
The pigpio Python module will probably be able to do this.
However to be sure you really need to explain what the PWM looks like. For instance square waves are much easier to detect than pulses with a 5% duty cycle.
If piscope can see the pulses the pigpio Python module should work.
Example code
#!/usr/bin/env python
import time
import pigpio
GPIO=[23,...
0
The system should not get that hot. However (as the last step before throwing the device into recycle bin) I would try to boot from clean unmodified system to be sure there is no software-related problem there.
1
I know you can do this with pigpio. I am not sure about the other Python modules.
SDA=2
SCL=3
pi = pigpio.pi()
if not pi.connected:
exit()
pi.write(SCL, 1) # automatically sets mode to WRITE
pi.write(SDA, 0) # automatically sets mode to WRITE
# read/write other GPIO
pi.write(SCL, 0)
pi.write(SDA, 1)
# read/write other GPIO
pi.set_mode(SDA, pigpio....
1
You can't use 5 V relay with signal from Raspberry Pi while Raspberry Pi signal is 3.3 V.
So if you used Logic level converter to convert 3.3 V from Raspberry to 5 V then to relay in I think it may solve this issue.
I don't know why most distributors say it should work with raspberry pi while the ideal one for Raspberry Pi is 3.3 ...
1
You can connect any LED that has a forward voltage of > 3 volts directly with a GPIO pin of a Raspberry.
To calculate the resistor:
Normally 10 mA is reasonably bright for a LED. However, if you want the maximum, check the Raspberry documentation for the recommended maximum current per output pin.
The steps are:
Find the forward voltage of the LED (Vf), ...
1
You must not connect a Pi GPIO to a voltage outside the range 0 to 3.3V. If you do so you will eventually destroy the GPIO and then the Pi.
Assuming you are using 3.3V.
Connect a GPIO to the green LED at the switch.
If the GPIO is high the green LED is on, otherwise the red LED is on.
3
You can use a break-out board like the Black HAT Hacker or Pico HAT Hacker.
Alternatively, connect another Pi Zero as a USB gadget and use the GPIO expander.
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